Method for retrofitting a building using a lift system and component kit for performing the method

ABSTRACT

A method for retrofitting a building using a lift system and a component kit for performing the method are provided. The shaft of the lift system extends over at least two stories  3  and comprises a self-supporting sheet metal box made of at least one steel plate, which is provided for receiving a cabin of the lift system together with its guides and drive devices. The sheet metal box of the shaft has a profiled cross section, which forms a cross-sectional area in the cross-sectional plane within the sheet metal box, which essentially covers the area required by the cabin and its guides and drive devices, and additionally contains the area of a lift platform for bridging a distance between the cabin and the building. The method provides prefabricating the lift system and installing it to the building.

INCORPORATION BY REFERENCE

The following documents are incorporated herein by reference as if fullyset forth: German Patent Application No. DE 10 2019 107 165.8, filedMar. 20, 2019.

TECHNICAL FIELD

The present invention relates to a method for retrofitting a buildingusing a lift system having a prefabricated shaft, and a component kitfor performing the method.

BACKGROUND

The prefabricated shaft extends over at least two stories and comprisesa self-supporting sheet metal box, which is provided for receiving acabin of the lift system together with its guides and drive devices,which may also contain a counterweight. The at least one steel platethat forms the self-supporting sheet metal box runs in a straight linein a longitudinal direction of the shaft, which corresponds to thedirection of movement of the cabin, while it is profiled in across-sectional plane that is orthogonal to the longitudinal directionof the shaft. Such a prefabricated shaft is known from EP 3 315 448 A2.

Traditionally, lift shafts consist of a concrete or steel structure thatis erected on site at the construction site. After the lift shaft hasbeen erected, the assembly of the actual lift system is generallycarried out on site by installing a cabin, its suspension and drive, andall the components required for operation. This results in a totalconstruction time of several weeks. This is particularly disadvantageouswhen the lift system is used to retrofit an existing and used building;that is because access to the building is difficult during theconstruction phase.

A solution to this problem has already been disclosed in BE 568 738. Itwas proposed therein to manufacture the shaft of the lift system from aplurality of thin-walled steel plates which abut one another at thecorners of the generally rectangular shaft and are connected to oneanother and stabilized there by means of profiles, angle irons and thelike. This made it possible to prefabricate the shaft as a sheet metalbox and even to install the cabin, its guides and drive devices in theshaft in the factory and only then to transport it to the constructionsite. The assembly time of the lift system could be greatly reduced dueto the high degree of prefabrication.

In order to improve the stability of a lift system having such aprefabricated shaft, EP 3 315 448 A2, already mentioned, proposes tofabricate the sheet metal box with which the shaft is manufactured fromat least one steel plate which runs in a straight line in thelongitudinal direction of the shaft, while being profiled in thecross-sectional plane; the at least one steel plate is preferably formedin one piece in the longitudinal direction over the entire extent of theshaft. This self-supporting and stable design of the sheet metal boxmakes it possible, on the one hand, to transport the prefabricated shaftfrom the factory to the construction site by means of a lorry; on theother hand, due to its inherent stability, the lift system manufacturedwith the self-supporting sheet metal box can be placed on an existingbuilding without being supported on the building, so that the statics ofthe building remain unaffected and there is no need to recalculate saidstatistics.

Lift systems for attaching to a building or for retrofitting a buildingare generally used in older buildings, in which no barrier-free accesshas yet been considered. In particular, residential buildings having aplurality of residential units, which are distributed over severalstories, but also administrative buildings and commercial buildings,often have a plurality of stories, which are in particular divided intoa plurality of residential units or other closed units and havecorresponding story doors. These story doors are usually accessible viaa common staircase. A common construction of such multi-story housesintegrates the staircase at the front side of the building with anentrance door at ground level and a double-flight of stairs that allowsaccess to all story doors via main landings on each story andintermediate landings. These are located on the main landings in thisconstruction.

It is obvious that people with disabilities in such buildings havelittle chance of getting to the story doors on their own. Even heavyobjects usually have to be transported via the staircase and cantherefore often not be made easier with the appropriate aids. It istherefore often desirable to retrofit such a multi-story building usinga lift system. One of the lift systems described above having aprefabricated shaft is offered for this purpose.

A lift system for attaching to a building from the outside or a methodfor retrofitting a building with such a lift system is known from DE 19633 636 A1. From this prior art, it can be seen that retrofitting thebuilding in this way only partially solves the problem of unhinderedaccess for people with walking difficulties. Due to the fact that whenthe retrofitted lift system is placed on the front side of the buildingin front of the staircase and the transitions between the shaft and thecorresponding building openings in the front side of the building aremade, a person who emerges from the lift cabin on the desired story canonly reach an intermediate landing of the staircase, so they would stillhave to climb half a story up or down by means of a stair section of thedouble-flight of stairs in order to access the story doors.

If a corresponding building is to be modernized to be largelybarrier-free by retrofitting a lift system, it has therefore nothitherto been the means of choice to use a prefabricated lift system ora prefabricated shaft of the type mentioned at the beginning. Instead,the staircase needs to be gutted and completely rebuilt using a liftsystem. Since access to the story doors is generally not possible duringthe corresponding construction period, one usually refrains fromretrofitting a corresponding building using a lift system, at least fromthe point of view of the greatest possible accessibility.

SUMMARY

The present invention is therefore based on the object of providing amethod for retrofitting a building using a lift system and a componentkit for performing this method, with which a building having a pluralityof stories and a staircase adjacent to a front side of the building and,per story, has a main landing and an intermediate landing for adouble-flight of stairs, can be retrofitted at least largelybarrier-free with a lift system.

This object is achieved by a method and a component kit having one ormore features of the invention.

Advantageous embodiments of the method according to the invention andpreferred developments of the component kit according to the inventionare described below ad in the claims.

The prefabricated shaft used according to the invention for a liftsystem to be attached to a building from the outside enables a buildingto be retrofitted using a lift system largely barrier-free even if thebuilding is accessed via a staircase having intermediate landings. Forthis purpose, the shaft extends over at least two stories and comprisesa self-supporting sheet metal box made of at least one steel plate,which is provided for receiving a cabin of the lift system together withits guides and drive devices, that is, also a counterweight ifnecessary. The at least one steel plate runs in a straight line in alongitudinal direction of the shaft, which corresponds to the directionof movement of the cabin, while it is profiled in a cross-sectionalplane orthogonal to the longitudinal direction of the shaft. The atleast one steel plate preferably extends in one piece in thelongitudinal direction of the shaft over the entire extent thereof,while two or more steel plates are joined to one another in thecircumferential direction, as is known per se. According to theinvention, the sheet metal box of the shaft has a cross section thatgoes beyond the mere enclosure of the cabin and the other components:the sheet metal box is profiled in such a way that a cross-sectionalarea is created in the cross-sectional plane within the sheet metal box,which cross-sectional area essentially contains the area required by thecabin and its guides and drive devices, and in addition the area of alift platform to bridge a distance between the cabin and the building.Preferably, the prefabricated shaft is fabricated with one lift platformper story.

Such a prefabricated shaft, placed in front of the front side of thebuilding, can cover the entire width of the staircase, so that it can beopened completely to the front side of the building when the building isretrofitted using the lift system. Since there is space within theprefabricated shaft for a lift platform that a person steps on afterleaving the cabin, the cabin can be arranged at a certain distance,namely the width of the lift platform, in front of the front side of thebuilding, which advantageously enlarges freedom of design inside thestaircase.

For buildings that have a staircase having intermediate landings and theground floor of which is half a story above ground level, it isessential to provide external access to the ground floor level after theintermediate landings have been removed without having to use the liftsystem. This is made possible by the concept of an additional liftplatform to bridge a distance between the cabin and the building. Suchexternal access can be created by opening access to the lift platformvia an outer staircase in addition to the cabin. Without a liftplatform, external access through a sheet metal box covering the entirewidth of the staircase on the front side of the building would only bepossible if an appropriate additional platform were installed inside thestaircase. However, the installation space is usually not sufficient forthis. The lift platform and the correspondingly designed cross sectionof the sheet metal box rather increase the area of the staircase. Thisis also the case when the building to which the lift system is to beattached does not contain a staircase having intermediate landings, sothat the prefabricated shaft used according to the invention offersadvantages even then.

Using the lift platform provided according to the invention, the trafficarea in front of the lift system in the staircase is expanded at thesame level; thus, with the concept according to the invention, therequirements for complete barrier-free access, which, in addition tolevel access, also require maneuvering areas of typically 1.5 m×1.5 m infront of a lift door, can be met without any problems.

Since the prefabricated shaft according to the invention is intended toretrofit a building using a lift system and thereby to cover the entirearea of the staircase at the front side of the building, it is preferredwhen the sheet metal box is provided with light openings in a walladjacent to the lift platforms. To increase the degree ofprefabrication, these light openings can already be equipped withwindows when the prefabricated shaft is transported to the constructionsite.

When the prefabricated shaft is provided with lift platforms, thesepreferably have anchoring devices for anchoring to elements of thestaircase, wherein these anchoring devices preferably produce a floatinganchor between the lift platform and a continuing platform or walkwayinside the staircase.

The sheet metal box of the prefabricated shaft is preferably essentiallyopen on the side which, in the assembled state, faces the front side ofthe building. In this way, the sheet metal box enlarges the enclosedspace of the staircase, and in particular the lift platforms become partof the staircase. In the area in which the cabin moves within the sheetmetal box, this building side of the shaft can be provided with crossstruts and sheathings, so that only one passage opening for entering andexiting the cabin remains free.

The sheet metal box of the prefabricated shaft preferably has a passageopening on one side that is not the building side, which passage openingis located in a position in which the lift platform for the ground floorof the building is located after the lift system has been attached to abuilding. This passage opening thus forms the front door to be madeaccessible via an outer staircase, through which one can get into thebuilding or the staircase bypassing the lift system. In addition, thereare advantages when a further passage opening is added on the groundlevel on one side of the sheet metal box, which side is not the buildingside of the shaft, and through which the cabin inside the shaft isaccessible from the outside at ground level. This ensures barrier-freeaccess to the lift system, even when a building is retrofitted using theprefabricated shaft according to the invention, the ground floor ofwhich is half a story above the ground level.

The sheet metal box of the prefabricated shaft preferably has a bottomsurface which is provided with fastening elements for fastening theshaft to a foundation, wherein the fastening elements advantageouslyhave adjustment devices in order to be able to align the shaftvertically on the foundation.

For buildings whose entrance and staircase are arranged on the front,the prefabricated shaft must be set up on this front side. However, thesupply lines for fresh water, waste water, electricity and informationtechnology usually run there at a depth of typically 1.20 m below groundlevel. A conventional prefabricated shaft is provided with an underpassbelow the lowest station of the cabin, in particular to providesufficient movement path for a counterweight of the cabin. Since thelowest station approached by the cabin should be on ground level forextensive accessibility, a correspondingly deep excavation is necessaryfor the foundation of the lift system to make room for this underpass.For this, however, the supply lines would have to be laid, which isassociated with corresponding effort and a period in which the buildingcannot be used. It is therefore preferred in the context of the presentinvention when the sheet metal box has a shortened underpass and isextended upwards in accordance with this shortening. This enables thefoundation for the lift system to be made to a depth that is still abovethe supply line. This depth is typically between 0.8 m and 1.0 m.

The lift system used according to the invention for attaching to abuilding from the outside comprises a prefabricated shaft describedabove, a cabin which can be moved in the longitudinal direction of theshaft, its guides and drive devices and a lift platform for each story.In order to increase the degree of prefabrication, the lift systempreferably also already comprises all doors and windows and a seal forjoining the shaft to the front side of the building. Due to the inherentstability of the sheet metal box used for the prefabricated shaft, thelift system according to the invention can be transported in theprefabricated state to the construction site by a lorry and set upthere.

The method according to the invention for retrofitting a building usinga lift system according to the invention is provided for a building thatcontains a plurality of stories, which are in particular subdivided andhave story doors which are accessible via a common staircase. Thestaircase is adjacent to the front side of the building and has, perstory, a main landing for the story doors and an intermediate landingfor a double-flight of stairs.

According to the method according to the invention, the lift system isfirst prefabricated in the factory. A foundation for the lift system isfabricated in front of the front side of the building. Regardless of thetime, the front side of the building is opened in the width of thestaircase, the intermediate landings and the double-flight of stairs areremoved, walkways are installed at the height of the main landings,which extend horizontally from the main landings to the front side ofthe building and thereby cover the cross section of the staircase onlypartially, in particular half, to leave clear space for a flight ofstairs, and a single-flight of stairs that connects the individualwalkways to one another and together forms a modified staircasetherewith is installed. Afterwards, the prefabricated lift system, afterbeing transported from the factory to the construction site, is set upon the foundation, aligned thereto and thereby joined to the front sideof the building. A connection is made between the lift platforms and thewalkways of each story, which is preferably designed to be floating inorder to enable a slight relative movement between the lift system andthe building. Finally, access to the lift platform of the ground flooris made from outside the building, preferably by attaching a front doorto the sheet metal box of the lift shaft and fastening an outerstaircase in order to be able to get from the ground level to the frontdoor.

Using the method according to the invention, it is possible for thefirst time to retrofit an existing and used building within a fewworking days, typically three to four days, with a lift system, largelybarrier-free, and then to free up the building again completely forunrestricted use. Due to the high degree of prefabrication of the liftsystem, the operational safety tests and approvals are limited to anacceptance test of the installed lift system on site, which cantypically be done within a day.

According to a preferred embodiment of the method according to theinvention, the contact points between the lift system and the front sideof the building are sealed, in particular using assembly foam and/or anelastomeric sealing element. This can be, for example, a U-profile or ahose that is filled with fire protection foam.

To fabricate the foundation for the lift system in front of the frontside of the building, an excavation for a shallow foundation ispreferably made, in particular with a case bottom of approx. 0.8 m to1.0 m depth, so as not to impair any supply lines that are typicallylaid at a depth of approx. 1.2 m.

The foundation itself is preferably prepared as a foundation plate froma one-part or multi-part precast concrete part. This has the advantagethat the foundation plate does not have to be concreted on site, but canbe delivered in a completed state by lorry. For this purpose, thefoundation plate can be formed in several parts, wherein each precastconcrete part that is to become part of the foundation plate hasdimensions and a weight with which transport on a normal lorry ispossible.

The foundation plate is preferably made from two precast concrete partswhich are initially not connected to one another. Only after the liftsystem has been set up on the foundation are the two precast concreteparts indirectly fastened to one another, in that the shaft of the liftsystem is partly fixed to the first and partly to the second precastconcrete part.

For the single-flight of stairs that connects the individual walkways toone another and forms a modified staircase therewith, straight stairsections having a quarter-turn entrance and exit, or having a quarterplatform at the entrance and exit, are preferably used. This shape ofthe stair sections makes the intermediate landings superfluous; the mainlandings are also preferably not part of the flight of stairs, ratheronly the walkways connect the individual stair sections on the way up ordown. This can be very advantageous, in particular with regard tocomplete barrier-free access to the staircase, because the main landingsare preserved as mere maneuvering areas.

In an alternative embodiment, straight stair sections having only aquarter-turn entrance or exit can be used, wherein the stair sections,depending on the orientation of their slope, begin or end on the mainlanding or use the main landing as a quarter platform of the flight ofstairs.

According to the invention, two alternatives are provided for installingthe walkways and the single-flight of stairs to replace the removedintermediate landings and the double-flight of stairs:

According to a first alternative, a crossbeam is used before installingthe walkways, which crossbeam is fastened on both sides of the staircaseto the outer walls of the front side of the building, and on which therespective walkway is placed. Here, the removal of the intermediatelandings and the double-flight of stairs and the installation of thewalkways and the single-flight of stairs are carried out in successivepartial sections from top to bottom, for example, using a liftingplatform.

According to a second alternative, the walkways and the single-flight ofstairs are installed by installing a preassembled staircase module. Theprocedure is therefore not successive, but rather the staircase is firstgutted by removing the intermediate landings and the double-flight ofstairs in order to be able to use the staircase module in one piece. Thestaircase module in this case contains at least the walkways and thestair sections which connect the walkways over a single-flight andpreferably have a quarter-turn entrance and/or exit. In addition, thestaircase module contains, as an essential element, a holding structureto which the walkways and the stair sections are fastened and whichpreferably consists essentially of a number of interconnected profilesor tubes which run in the stairwell and connect all walkways to oneanother.

To simplify the installation of the staircase module, a separatebasement staircase module is preferably used, which comprises asingle-flight stair section and support for the staircase module, andwhich is installed before the staircase module is installed by insertingit into the gutted staircase and is set up there on the basement floor.

The installation of the staircase module is particularly easy when, inaddition, auxiliary rails for sliding in the staircase module into thebuilding are installed on the ground level and the staircase module canbe slid in through the open front side of the building by means of theauxiliary rails. The foundation for the lift system is expedientlycovered before the auxiliary rails are attached, in order to avoid anydamage to the foundation. After the staircase module has been slid in,the auxiliary rails can be removed or cut to length, and the staircasemodule essentially rests on the supports of the basement staircasemodule. In addition, the walkways of the staircase module can beconnected to building walls and/or the main landings. Such a staircasemodule in turn increases the degree of prefabrication when retrofittinga building using a lift system, whereby the construction time for theretrofitting is shortened again.

Finally, the present invention also comprises a component kit forperforming the method according to the invention, wherein this componentkit comprises at least one prefabricated shaft according to theinvention and a preassembled staircase module, wherein the staircasemodule consists of one walkway for each story and of stair sectionswhich connect the walkways over a single flight, and a holding structureto which at least the walkways and preferably also the stair sectionsare fastened.

The holding structure of the preassembled staircase module preferablyconsists essentially of a number of interconnected profiles or tubeswhich run in the stairwell and connect all the walkways to one another.

The stair sections of the preassembled staircase module are preferablydesigned as stair sections having a quarter-turn entrance and/or exit orhaving a quarter platform at the entrance and/or exit.

The component kit according to the invention can also comprise afoundation plate made of a one-part or multi-part precast concrete part,and a separate basement staircase module having a single-flight stairsection and supports for the staircase module.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of a lift system designed according to the invention andan embodiment for performing a method according to the invention aredescribed and explained in more detail with reference to theaccompanying drawings. Shown are:

FIGS. 1 to 20 different phases in the performance of an embodiment for amethod according to the invention, in a schematic representation;

FIG. 21 a lateral cross section through a staircase of a building fromFIGS. 1 to 20, using a retrofitted lift system;

FIGS. 22A-22C three sections with views of the staircase from FIG. 21from above, namely through the basement, through the ground floor andthrough an upper story;

FIG. 23 a cross section through the lower half of the staircase,according to another embodiment;

FIG. 24 a part of a lateral cross section as in FIG. 21, but accordingto another embodiment; and

FIG. 25 a section having a view from above as in FIG. 22C, but accordingto the embodiment from FIG. 24.

DETAILED DESCRIPTION

The method shown schematically illustrated in FIGS. 1 to 20 in selectedmethod steps and designed according to the invention is an example ofthe retrofitting according to the invention of a used residentialbuilding using a lift system according to the invention, which can becarried out on site within three working days.

FIG. 1 shows schematically a front side 1 of a four-story building, theground floor of which is half a story height above ground level 2. Atotal of eight flats are accommodated in the four stories 3 above groundlevel 2, which flats are accessible via story doors 4. These make theflats accessible via a central staircase 5, which is adjacent to thefront side 1 of the building and can be entered from the outside via afront entrance 6.

FIG. 2 shows the staircase 5 in greater detail. It is thus clear thatthe staircase 5 contains, in addition to eight story doors 4 for eachstory, a main landing 7, which is associated with the story doors 4, andan intermediate landing 8 for two flights of stairs 9. It is also clearhere that the front entrance 6, which is located on ground level 2,leads to an intermediate landing for the double-flight of stairs 9, sothat access to the ground floor can only be reached via a stair sectionof the double-flight of stairs.

FIG. 3 symbolizes the pick-up of residents who move to a hotel for thethree-day construction work.

FIG. 4 shows that the construction work begins with an excavation 10 fora shallow foundation of the lift system (not yet illustrated here) andin parallel with a cut 11 for opening the front side 1 of the buildingin the width of the staircase 5.

In order to protect any supply lines of the building for fresh water,waste water, electricity and/or data traffic against excessive loads, asshown in FIG. 5, a specific cover 12 can be attached in the excavation10. The excavation 10 is typically 0.8 m to 1.0 m deep, so that thesupply lines can remain in place.

FIG. 6 symbolizes the delivery and insertion of a first precast concretepart 13 as part of a foundation plate 14 into the excavation 10, whilethe opening of the front side 1 of the building proceeds.

In FIG. 7, a second precast concrete part 13′ has been delivered andinserted into the excavation 10, so that the foundation plate 14 hasalready been completed.

As FIG. 8 shows, the foundation plate 14 is then protected by placing afoundation cover 15 for the further construction work.

FIG. 9 illustrates schematically that after opening the front side 1 ofthe building, the double-flight of stairs 9 and the intermediatelandings 8 are removed from the staircase 5. The main landings 7,however, remain in place.

As FIG. 10 shows, a basement staircase module 16 is then introduced intothe staircase 5 and placed on the floor of the basement. This basementstaircase module 16 essentially consists of a stair section 23 and asupport 17 for setting up a staircase module (not yet illustrated here).

FIG. 11 illustrates how three auxiliary rails 18 are introduced into thestaircase 5 on ground level 2, namely one auxiliary rail 18 each on theside walls of the staircase 5 and a third auxiliary rail 18 on thesupport 17 of the basement staircase module 16. The auxiliary rails 18run over the foundation cover 15 here.

As shown in FIGS. 12, 13 and 14, a staircase module 19, which wasprefabricated in the factory and can be delivered using a lorry 20 dueto a corresponding inherent stability, is then lifted from the lorry 20by a crane lorry 21, placed on the auxiliary rails 18 and slid into thestaircase 5 along the auxiliary rails 18. The staircase module 19 hereconsists of a single-flight of stairs 22 having individual stairsections 23, each of which has a quarter-turn entrance and exit, inorder to connect a walkway 24 for each story to the walkway 24′ locatedbelow or above it. In particular, FIG. 15 illustrates here that thequarter-turn stair sections 23 continue to maintain the main landings 7with regard to desirable barrier-free accessibility as maneuveringareas; the same applies to the lift platforms 35 (not shown here) (seeFIGS. 21 to 23).

The staircase module 19 obtains the necessary inherent stability througha holding structure 25 which is arranged in the stairwell and comprisesa plurality of vertically running steel tubes which connect theindividual walkways 24, 24′ to one another and finally transfer the loadonto the support 17 of the basement staircase module 16.

After making connections between the walkways 24 and the main landings7, and optionally after additional securing of the walkways 24 and/orthe stair sections 23 on the side walls of the staircase 5, thefoundation cover 15 is removed again and the auxiliary rails are scaledback by cutting to length. FIG. 15 shows this state.

The construction site is thus prepared for the delivery of a lift system26 designed according to the invention, which in turn is delivered usinga lorry 20 and is lifted and set up by a crane lorry 21, as shown inFIGS. 16 and 17. The lift system 26 here consists of a prefabricatedshaft 27 designed according to the invention, in which a (not visiblehere) cabin is installed together with its guides and drive devices andother devices necessary for operation. The shaft 27 also comprises liftplatforms (not visible here) for each story and a number of lightopenings 28 with windows, a front door 29 and a ground-level passageopening 30 positioned on ground level 2 for operating the cabin guidedin the shaft 27.

As FIG. 17 shows, the lift system 26 is set up on the foundation plate14 and then aligned and fixed. At the same time, the contact surfacesbetween the shaft 27 and the front side 1 of the building are sealedwith fire protection foam. As can be seen from FIG. 17, the shaft 27covers the entire width of the staircase 5, so that the front side 1 ofthe building is closed again after the lift system 26 has been set up.

In order to create an escape route or access to the staircase 5 and tothe individual story doors 4 bypassing the lift, the front door 29,which is now located at the level of the ground floor, since it leads tothe ground floor lift platform, from where the ground floor walkway 24and the ground floor main landing 7 can be reached, is equipped with anouter platform 31 and an outer staircase 32.

After removal of the lift system 26 and attachment of handrails 33 and acanopy 34, as shown in FIG. 19, the retrofitting of the building withthe lift system 26 is completed and, as shown in FIG. 20, the residentscan move into their flats again.

FIG. 21 illustrates the result of an embodiment of a method according tothe invention in a lateral sectional illustration through the staircase5. The associated FIGS. 22A-22C show sectional views from above throughthe basement (FIG. 22A), through the ground floor (FIG. 22B) and throughone of the upper stories (FIG. 22C), which in particular illustrates theconstruction according to the invention of the lift system 26 or theprefabricated shaft 27.

As FIG. 21 shows, the staircase 5 consists of four above-ground stories,a ground floor and three upper stories, and a basement. The story doors4 each open onto a main landing 7 which has remained in its originalstate. The front side 1 of the building has been opened, and the mainlandings 7 have been connected at the same level to lift platforms 35 bymeans of inserted walkways 24 fastened to the staircase side walls,which were joined together with the prefabricated shaft 27 to the frontside 1 of the building. The shaft 27 stands here on a foundation plate14, which was previously inserted in front of the front side 1 of thebuilding in a corresponding excavation 10.

At ground level 2, an outwardly oriented passage opening 30 can bereached in the shaft 27, through which a cabin (not illustrated here)that is movable within the shaft 27 in the longitudinal direction isaccessible. Alternatively, access to the staircase 5 via the outerstaircase 32 and the front door 29 to the ground floor lift platform 35is ensured, from where the single-flight of stairs 22 with the walkways24 can be reached without having to use the lift system 26.

As FIG. 21 illustrates, each level of each main landing 7 or each storydoor 4 can be reached directly via the lift system 26, and each storydoor 4 can be reached by the lift system 26 at the same level via thelift platform 35, the walkway 24 and the main landing 7 without anybarriers.

The stair sections 23 having quarter-turn entrance and exit prevent themain landings 7 and the lift platforms 35 from having to be part of thesingle-flight of stairs 22. Rather, they can be used as mere traffic andmaneuvering areas in the sense of complete accessibility. Appropriatehandrails ensure the necessary traffic safety.

The central function of the lift platform 35 is illustrated using FIG.22, in particular FIG. 22B. This is the only way to ensure an escaperoute or access to the staircase 5 without having to use the lift system26. Due to the fact that since the ground floor, which is half a storyabove ground level 2, can only be reached at the same level from thefront side 1 of the building via a walkway 24, an outer staircase 32must be provided, via which one can get from ground level 2 to walkway24. If the cabin 36 of the lift system 26 were not spaced apart from thefront side 1 of the building, as is the case here, but rather openeddirectly towards the walkway 24, it would not be possible to access thewalkway 24 via the outer staircase 32. At the same time, the liftplatform 35 increases the area of the staircase 5 since the shaft 27with its lift platform 35 covers the entire width of the staircase 5 andthereby closes the front side 1 of the building again.

FIG. 22A moreover again illustrates that the foundation plate 24 iscomposed of two precast concrete parts 13, which are indirectlyconnected to one another by fastening each precast concrete part 13, 13′to the lift system 26. The stair section 36, which leads from thebasement to the ground floor, has a quarter-turn entrance, but astraight exit, since it is part of the basement staircase module 16,which ultimately forms a support 17 for the staircase module 19.

The design of the modified staircase having a single-flight of stairs22, which, as in the embodiment according to FIGS. 1 to 20, is formed bya prefabricated staircase module 19 and a basement staircase module 16,is illustrated again in more detail in a partial sectional lateral viewin FIG. 23. It can also be seen here that the stair sections 23, likethe holding structure 25 of the staircase module 19, are prefabricatedfrom steel profiles.

FIG. 24 is a lateral sectional view through the staircase 5 according toanother embodiment in comparison to the embodiment illustrated in FIG.21. Here again, a prefabricated staircase module was used, which differsfrom the embodiment according to FIG. 21 in that the individual stairsections 23 are straight, that is, they do not have any quarter-turnedentrances and exits.

Using this construction, the main landings 7 and the lift platforms 35are also used as part of the single-flight of stairs 22, as can beclearly seen from FIG. 25, a section with a view of the staircase fromFIG. 24 from above, namely through an upper story. As can be seen fromthis figure, it is a relatively wide staircase, so that the shaft 27having the cabin 36 can be joined asymmetrically to the staircase 5 andthe lift platform 35 in such a way that the traffic space in front ofthe cabin 36, which is necessary for accessibility or accessibilitydesign, does not coincide with that area of the lift platform 35, onwhich the straight stair section 23 is joined and which would thereforehave to be regarded as part of the single-flight of stairs 22.

If the staircase has a sufficient width for an embodiment according toFIGS. 24 and 25, it can be advantageous for cost reasons to form thesingle-flight of stairs 22 from straight-line stair sections 23.

1. A method for retrofitting a building with a lift system, the buildingcontaining a plurality of stories (3) which are subdivided and havestory doors (4) which are accessible via a common staircase (5), thestaircase (5) being adjacent to a front side (1) of the building and,for each story (3), having a main landing (7) for the story doors (4)and an intermediate landing (8) for a double-flight of stairs (9), themethod comprising: prefabricating the lift system (26) having a shaft(27), having a cabin (36) which is movable in a longitudinal directionof the shaft (27), with guides and drive elements, and a lift platform(35) for bridging a distance between the cabin (36) and the building foreach story (3), the shaft (27) extending over at least two stories (3)and comprising a self-supporting sheet metal box made of at least onesteel plate, which is provided for receiving the cabin (36) togetherwith the guides and the drive elements, said sheet metal box extends ina straight line in the longitudinal direction of the shaft (27) whilebeing profiled in a cross-sectional plane orthogonal to the longitudinaldirection of the shaft (27), and the sheet metal box of the shaft (27)having a cross section which forms a cross-sectional area in thecross-sectional plane within the sheet metal box, the cross-sectionalarea containing an area required by the cabin (36) and the guides andthe drive elements and additionally an area of the lift platform (35),fabricating a foundation (14) for the lift system (26) in front of thefront side (1) of the building, opening the front side (1) of thebuilding in a width direction of the staircase (5), removing theintermediate landings (8) and the double-flight of stairs (9),installing walkways (24) at a height of the main landings (7), whichextend horizontally from the main landings (7) to the front side (1) ofthe building and thereby only partially cover the cross section of thestaircase (5) to provide clear space for a flight of stairs, installinga single-flight of stairs (22) which connects the individual walkways(24) to one another and forms a modified staircase therewith, setting upthe lift system (26) on the foundation (14), aligning the lift system(26) on the foundation (14) and joining the lift system (26) to thefront side (1) of the building, establishing a connection between thelift platforms (35) and the walkways (24) on each story (3), andestablishing access to the lift platform (35) of the ground floor fromoutside the building.
 2. The method as claimed in claim 1, wherein theinstallation of the walkways (24) and the installation of thesingle-flight of stairs (22) is carried out by installing a preassembledstaircase module (19) which contains at least the walkways (24) andstair sections (23) which connect the walkways (24) over one flight, anda holding structure (25) to which the walkways (24) and the stairsections (23) are fastened.
 3. The method as claimed in claim 2, whereinthe holding structure (25) is formed of a number of interconnectedprofiles or tubes, running in a stairwell or between the walkways (24)and the stair sections (23) and connecting all of the walkways (24) toone another.
 4. The method as claimed in claim 3, further comprisingbefore the installation of the staircase module (19), installing abasement staircase module (16) having a single-flight stair section (23)and supports (17) for the staircase module (19).
 5. The method asclaimed in claim 4, further comprising before the installation of thestaircase module (19), attaching auxiliary rails (18) for sliding thestaircase module (19) into the building, and sliding the staircasemodule (19) in using the auxiliary rails (18) through the open frontside (1) of the building.
 6. The method as claimed in claim 1, furthercomprising sealing contact points between the lift system (26) and thefront side (1) of the building using at least one of assembly foam or anelastomeric sealing element.
 7. The method as claimed in claim 1,wherein the foundation is fabricated as a foundation plate (14) from aone-part or multi-part precast concrete part (13).
 8. The method asclaimed in claim 1, further comprising using straight stair sections(23) having at least one of a quarter-turn entrance or exit or having aquarter platform at at least one of the entrance or exit for thesingle-flight of stairs (22).
 9. The method as claimed in claim 1,further comprising using the shaft (27) for the lift system (26) toestablish access to the lift platform (35) of the ground floor fromoutside the building, the sheet metal box of which, in a position inwhich the lift platform (35) for the ground floor of the building islocated after the lift system (26) has been attached to the building ona side that is not a building side of the shaft (27), is provided with apassage opening for a front door (29), and attaching an outer staircase(32) to the shaft (27) which connects the passage opening of the shaft(27) to the ground level (2).
 10. The method as claimed in claim 1,further comprising, before the installation of the walkways (24), ineach case using a crossbeam, which is fastened on both sides of thestaircase (5) to the outer walls of the front side (1) of the building,and placing the respective walkway (24) on the crossbeam.
 11. Acomponent kit for performing the method as claimed in claim 1,comprising: the shaft (27) for the lift system and the preassembledstaircase module (19), the staircase module (19) including a walkway(24) for each story (3) and the stair sections (23) which connect thewalkways (24) over a single flight, and a holding structure (25) towhich the walkways (24) and the stair sections (23) are fastened, andthe shaft (27) extending over at least two of the stories (3) andcomprising the self-supporting sheet metal box made of the at least onesteel plate for receiving the cabin (36) together with the guides anddrive elements, the sheet metal box extending in a straight line in thelongitudinal direction of the shaft (27), and being profiled in thecross-sectional plane orthogonal to the longitudinal direction of theshaft (27), and the sheet metal box of the shaft (27) having the crosssection forming the cross-sectional area within the sheet metal box inthe cross section plane, the cross-sectional area containing the arearequired by the cabin (36) and the guides and drive elements andadditionally the area of the lift platform (35).
 12. The component kitas claimed in claim 11, wherein the holding structure (25) includes anumber of interconnected profiles or tubes which extend in the stairwellor between the walkways (24) and the stair sections (23) and connectingall of the walkways (24) to one another.
 13. The component kit asclaimed in claim 11, wherein the stair sections (23) include at leastone of quarter-turn entrance or exits or having a quarter platform at atleast one of the entrance or exit.
 14. The component kit as claimed inclaim 11, further comprising a foundation plate (14) made of a one-partor multi-part precast concrete part (13).
 15. The component kit asclaimed in claim 11, further comprising a basement staircase module (16)having a single-flight stair section (23) and supports (17) for thestaircase module (19).
 16. The component kit as claimed in claim 11,wherein the shaft (27) comprises the sheet metal box and the liftplatform (35) for each said story (3).
 17. The component kit as claimedin claim 11, wherein the lift platforms (35) are provided with anchoringdevices for anchoring to elements of the staircase (5) of the building.18. The component kit as claimed in claim 11, wherein the sheet metalbox is open on a building side of the shaft (27).
 19. The component kitas claimed in claim 11, wherein the sheet metal box is provided withlight openings (28) in a wall adjacent to the lift platforms (35).